Method of producing a protein-free fluid



Feb. 3, .1970 M. MASS 3,493,503

METHOD OFPRODUCING A PROTEIN-.FREEFLUID Filed May 19, 1967 INVENTORWflW/J/VASS ATTO NEYS United States Patent O 3,493,503 METHOD OFPRODUCING A PROTEIN- FREE FLUID Morris Mass, Kew Gardens, N.Y., assignorto Haematronics, Inc., New Rochelle, N.Y., a corporation of New YorkFiled May 19, 1967, Ser. No. 639,742 Int. Cl. B011: 9/02 U.S. Cl. 210-594 Claims ABSTRACT OF THE DISCLOSURE The present invention includesapparatus for producing a protein-free fluid and comprises a syringe forinitially containing a protein-bearing fluid and filter meanscooperating with the syringe for inhibiting passage of proteintherethrough.

This invention relates to apparatus for measuring and indicating colordensity with respect to a standard, and more particularly to a syringefor producing a proteinfree fluid.

Use of protein-free filtrates and fluids are known. Present methods forpreparing and obtaining protein-free filtrates include the use offunnels, fluted filter paper and centrifuging apparatus. Obviousdrawbacks include the large amount of time required to prepare the fluidand thus make present methods undesirable and costly in the field ofclinical analysis.

An object of the present invention is to provide a novel syringestructure for use in producing a proteinfree fluid.

Another object of the present invention is to provide a method ofproducing a protein-free fluid including, in a preferred embodiment, theuse of a syringe.

Still another object of the present invention is to provide an extremelyinexpensive and very rapid method and apparatus for producing afiltrate.

A further object of the present invention is to provide improvedapparatus for measuring and indicating color density with respect to astandard in which, in a preferred embodiment, novel colorimeterapparatus is employed for determining the sugar content or otherproperty of a blood-donors blood.

A still further object of the present invention is to provide adisposable syringe for use in producing a filtrate wherein a pretreatedinsert is employed in forcing a fluid such as the mixture of fingertipblood and a reagent through the insert and into a receptacle.

Yet another object of the present invention is to provide a disposablesyringe structure having a barrel and a plunger wherein the plunger isremovable and replaceable.

Another object is to provide means for indicating the properties ofblood wherein fingertip blood is utilized and the need for removal ofvenous blood from the donor is eliminated.

The present invention fulfills the aforementioned objects and overcomeslimitations and disadvantages of prior art solutions to problems byproviding a disposable syringe structure for use in preparing aprotein-free fluid. In one embodiment of the present invention, adisposable syringe includes a barrel portion and a plunger assemblywhich matingly cooperate and are constructed to permit removal of theplunger assembly from the barrel. The barrel comprises an elongatedsubstantially cylindrical middle portion which extends from a perforatedend to an open end having flared beariing surfaces. The open end isadapted to receive a disposable and removable filter insert which,during use of the present embodiment, is

disposed within the barrel adjacent the perforated end thereof.Insertion of the filter insert is accomplished by placing a pretreatedfilter paper disc into the entrance portion of the open end of thebarrel and matingly engaging the plunger assembly into the barrel so asto bias the insert further into the barrel and downward towards theperforated end until it is in place.

The plunger assembly includes a shank portion which extends between abearing cap having a bearing surface for pressure to be applied theretowith the hand of the user of the present invention, and a resilientpiston having at least one diameter which is adapted to slidably engagethe interior portion of the barrel such that a liquid-tight seal isachieved during movement of the plunger toward and away from theperforated end of the barrel.

In operation, the barrel is placed in one hand of the user; the filterinsert is placed into the entrance portion of the open end of thebarrel; the plunger assembly is used to force the insert into thebottommost portion of the barrel adjacent the perforated end thereof;the plunger assembly is thereafter removed from the barrel; a suitableand predetermined reagent in selected quantities is placed through theopen end of the barrel and into the inside thereof; a selected amount offingertip blood is added to the reagent within the barrel; the twosubstances are mixed, such as by tapping an extremity of the barrel; theplunger assembly is inserted into the barrel and, by forcing the plungerassembly toward the perforated end, the piston assembly forces themixture within the barrel to pass through the filter insert which willpermit only protein-free fluid to pass therethrough and out of thebarrel through the perforations in the perforated end and thereafterinto a suitable receptacle.

The invention will be more clearly understood from the followingdescription of a specific embodiment of the invention, together with theaccompanying drawing, wherein similar reference characters denotesimilar elements throughout the several views, in which:

FIG. 1 is an exploded perspective view of the elements of a syringeassembly;

FIG. 2 is a fragmentary sectional elevation view of the syringe assemblyshown in FIG. 1;

FIG. 3 is an enlarged bottom view of the perforated end of the barrelassembly shown in FIG. 1;

FIG. 4 is a sectional elevational view of a test tube shownfragmentarily in FIG. 2, for use in a colorimeter; and

FIG. 5 is a view taken along the line V-V of FIG. 2.

Referring now in detail to the drawing, in FIG. 1 a syringe assembly 1is shown in an exploded view as including a barrel assembly 2, a filterinsert 3 and a plunger assembly 4.

Barrel assembly 2 includes a cylindrical middle portion 5 which extendsbetween a perforated end 6 and an open end 7. Perforated end 6 has aplurality of holes 8 formed therethrough, which holes are adapted topermit fluid to pass through perforated end 6 at a predetermined rate asa function of the force exerted by the plunger assembly. FIG. 3illustrates, in one embodiment, five holes formed through end 6.

Flanged or flared portions 9 form an integral part of barrel assembly 2and extend substantially perpendicularly in diametrically oppositedirections from middle portion 5. Bearing surfaces 10 are provided forgripping of the underside of flared portions 9 by the fingers of theuser of syringe assembly 1. The thickness of flared portions 9 ispredetermined in order to withstand the stresses induced in flaredportions 9 during the bearing of the fingers of the user against thebearing surfaces 10. Bearing surfaces 10 assume a semielliptical shapefor the flared portions shown in the embodiment in FIG. 1.

Filter insert 3, as shown in FIG. 1, includes a cylindrical disc havingsurfaces 11 which lie in substantially parallel planes. The thickness ofinsert 3 is predetermined and may be a function of the volume and massflow rates that insert 3 will accommodate.

Plunger assembly 4 includes a shank portion 12 having a cross-shapedribbed cross section including four outwardly extending ribs 13. Shankeportion 12 extends between a bearing cap 14 and a piston assembly 15.Bearing cap 14 is integral with shank portion 12 and may be eitherformed therewith, such as by molding or machining, or may be attached toshank portion 12 such as by welding or fusing methods. Bearing cap 14comprises a bearing surface 16 (FIG. 2) which is void of sharp edges andis of circular dimensions suitable for the application of the thumb orother portion of the hand of a user thereto.

FIG. 5 illustrates a preferred cross-sectional construction of shankportion 12 wherein favorable strength properties may be achieved. LetterH designates the maximum overall cross-sectional dimension of shankportion 12 and letter h designates the thickness of ribs 13 in thesymmetrical configuration shown in FIG. 5. The shear and bendingproperties of the shank portion of plunger assembly 4 may bepredetermined by selecting values for H and h which will yield favorablecharacteristics, depending upon the applications in which the presentsyringe structure will be used. In computing the shear strength of shankportion 12, the cross-sectional area A, being a function of H and h isPiston assembly 15 includes a resilient member 16 of stepped diametersand having conical portions. Portion 17 originates at a first diameterand has a truncated conical cross-section terminating at portion 18.Portion 18 is cylindrical and possesses a constant given diameter ofabsolute magnitude less than diameter D, which designates the insidebore diameter of middle portion 5 of barrel assembly 2. Portion 19originates at portion 18 and has a cross-section which is substantiallya mirror image of the cross-section of portion 17, thereby terminatingat said first diameter. Portion 20 is of conical cross-section with theapex thereof directed toward perforated ends '6 when plunger assembly 4is inserted into barrel assembly 2. Said first diameter may be equal orslightly greater than diameter D of middle portion 5 and, in a preferredembodiment wherein the first diameter is larger than diameter D, thepiston assembly 15 and its associated integral portions 17-20 which makeup member 16 will yield and bear against the inside surface 21 of middleportion 5 of barrel assembly 2. Thus the engagement of member 16 againstinside surface 21 will provide a liquid-tight seal which will preventthe passage of fluid past member 16 during relative movement of member16 with respect to portion 50.

Member 16 may be removable and of a predetermined and selectedcross-section apart from that shown in FIG. 2 such that, depending uponthe sealing characteristics desired, member 16 may be selected from aseries of disposable members having different physical configurations.Portion 22 of plunger assembly 4 is provided with means for removablysecuring member 16 thereto.

Filter insert 3, in one embodiment in the present invention, is apretreated disc of filter paper. In preparing insert 3, a large sheet,from which several discs are cut, is soaked in a solution in whichsodium tungstate is mixed or dissolved in water. After the sheet issoaked in the tungstate solution, it is removed and dried and thereaftersuitable sized inserts are cut from the sheet.

In operation, the user of syringe assembly 1 places filter insert 3inside open end 7 and, with the use of plunger assembly 4, pushes insert3 down into middle portion 5 until the insert is adjacent perforated end6 as shown in FIG. 2. Thereafter, plunger assembly 4 is removed frombarrel assembly 2 and barrel assembly 2 is caused to stand vertically asshown in FIG. 2. A stable tungstic acid solution or mixture is splaced,in predetermined amounts, into barrel assembly 2, which acid may containsodium tungstate. Thereafter, predetermined amounts of fingertip blood,as opposed to venous blood, are added to the solution Within barrelassembly 2. The two fluids are mixed, such as by tapping perforated end6 with the finger tip until a mixture is achieved. Plunger assembly 4 isthen inserted into barrel assembly 2 in the position in FIG. 2 andforced with the hand of the user into the barrel assembly such thatfluid 23 within middle portion 5 is forced against insert 3. Sinceinsert 3 is adapted to permit only protein-free fluid to passtherethrough, such protein-free fluid emerges from the downward surface11 of insert 3 and flows through holes 8 in perforated end 6 andthereafter into a test tube 24 (FIG. 2). Thus, as seen in FIG. 4, testtube 24 will contain fluid 25 which is protein-free and suitable for usein apparatus such as a colorimeter for measuring sugar content of blood.

A copper reagent in the form of a solution containing one part of 5%CUSO two parts of citric acid, and l/ 100 of a part of phosphoric acidis added to the protein-free fluid collected in the test tube 24 orother suitable receptable. Glucose in the blood of the donor will engagecopper in the copper reagent to form a mixture. This mixture is placedin boiling water for a predetermined time, such as five minutes, whichwill result in the formation of cuprous oxide, the density of thecuprous oxide being proportional to the amount of glucose in the blood.The mixture is thereafter removed and allowed to cool. A color reagentis added to the cooled mixture, the color reagent in the form ofphosphomolybdic acid which contains molybdic anhydride, sodium carbonateand a stabilizer (EDTA). The molybdenum in the coloring agent will reactwith the cuprous oxide to form a blue color, the intensity of the bluecolor being a function of and being proportional to the density of thecuprous oxide in the cooled solution. Thus it is seen that the colorintensity of the final fluid is directly pro portional to the amount ofglucose in the blood of the blood donor from which fingertip blood wastaken. By measuring the color intensity of this solution with respect toa standard solution, the glucose reading of a persons blood may berapidly and easily determined.

It is this blue color solution that is thereafter inserted into acolorimeter, such as disclosed in my US. patent application, Ser. No.685,431, filed on Nov. 24, 1967, such that a light source is passedthrough the solution and the light emerging from the solution impinges aphotoelectric cell after passing through a suitable filter, whichphotoelectric cell is electrically connected to a meter which will givethe user of the meter and the reader thereof an immediate indication ofthe percentage of glucose in the blood of a person who donates fingertipblood.

It is, of course, within the scope of the present invention to includethe disclosed method and apparatus for determining other properties offluids such as blood, besides glucose.

The embodiment of the invention particularly disclosed is presentedmerely as an example of the invention. Other embodiments, forms andmodifications of the invention coming within the proper scope of theappended claims will of course readily present themselves to thoseskilled in the art.

What is claimed is:

1. A method of producing a protein-free fluid, comprising the steps ofplacing disposable filter means into an opening of the barrel of asyringe, pushing said filter means into said barrel with a plungerassembl removing said plunger assembly from said barrel, placing apredetermined amount of tungstic acid reagent through said opening intothe barrel, adding a fingertip blood of a donor to the reagent Withinsaid barrel, causing said blood and said reagent to mix With one anotherto form a mixture, reinserting said plunger assembly into said barreland forcing said mixture against and through said filter means therebycausing a protein-free filtrate to be discharged from the syringe.

2. The method as defined in claim- 1, wherein said filter is a disc offilter paper comprising impregnating said paper with a tungstatesolution before passing said mixture therethrough.

3. A method of producing a protein-free fluid, comprising the steps ofplacing disposable filter means into an opening of the barrel of asyringe, pushing said filter means into said barrel with a plungerassembly, removing said plunger assembly from said barrel, placing apredetermined amount of sodium tungstate reagent through said openinginto the barrel, adding a fingertip blood of a donor to the reagentwithin said barrel, causing said blood and said reagent to mix with oneanother to form a mixture, reinserting said plunger assembly into saidReferences Cited UNITED STATES PATENTS 2,306,325 12/ 1942 Allam.

850,357 4/1907 Doyle 128-234 3,316,909 5/1967 COWley 128-234 X OTHERREFERENCES Peters, J. P., et al.: Quantitative Clinical Chemistry, vol.II, Methods, 1932, Williams & Wilkins (30., Baltimore, pp. 64-66 reliedon.

Aloe Laboratory Apparatus-Equipment-Reagents, Catalog No. 103, 1952,published by Aloe Scientific, St. Louis, Mo., p. 396 relied on.

MICHAEL E. ROGERS, Primary Examiner US. Cl. X.R.

